This invention relates generally to physiological drainage systems, and, more specifically, to a siphon control device for limiting fluid flow through such systems due to the siphoning effect of hydrostatic pressure.
In the medical arts, to relieve undesirable accumulation of fluids it is frequently necessary to provide a means for draining a fluid from one part of the human body to another in a controlled manner. This is required, for example, in the treatment of hydrocephalus, an ailment usually afflicting infants or children in which fluids accumulate within the skull and exert extreme pressure and skull deforming forces.
In treating hydrocephalus, cerebrospinal fluid accumulated in the brain ventricles is typically drained away utilizing a drainage or shunt system including a catheter inserted into the ventricle through the skull, which is connected to a tube which conducts the fluid away from the brain to be reintroduced into the peritoneal cavity or into the vascular system, as by extending a distal catheter through the patent's jugular vein to the atrium portion of the heart. To control the flow of cerebrospinal fluid and maintain the proper pressure in the brain ventricle, a pump or valve is placed in the conduit between the brain and the peritoneal cavity or the heart. Exemplary valves are found in U.S. Pat. Nos. 4,552,553 and 4,560,375, the contents of which are incorporated by reference herein.
Although such drainage systems have provided successful results, a problem of overdrainage of the cerebrospinal fluid from the brain ventricles sometimes exists. Overdrainage of cerebrospinal fluid may result in excessive reduction of the cerebrospinal fluid pressure within the brain ventricles and predispose the development of a subdural hematoma or hydroma, and excessive reduction of ventricular size leading to shunt obstruction because of impingement of the ventricular walls on the inlet holes of the ventricular cathether. This overdrainage can be caused by the siphoning effect of hydrostatic pressure in the distal shunt catheter. The siphoning effect of hydrostatic pressure may be created by the elevation of the ventricular catheter inlet with respect to the distal catheter outlet (i.e., when the patient sits, stands or is held erect).
Accordingly, there has been a need for a novel subcutaneously implantable siphon control device for use in a physiological shunt system which can effectively prevent overdrainage of fluid through the system due to the siphoning effect of hydrostatic pressure. It would be preferable that such a novel siphon control device be normally closed, open only in response to positive upstream fluid pressure, and re-close or remain closed in the absence of such positive upstream fluid pressure or in response to negative downstream hydrostatic pressure. Further, a siphon control device is needed which utilizes dissimilar materials to inhibit component sticking and deformation, and which includes integral connectors. Moreover, a siphon control device is needed which has an uncomplicated internal flow path and design which eliminates anterior/posterior positioning concerns. The present invention fulfills these needs and provides other related advantages.